Rubber dome for underwater sound



1951 J. w. FITZGERALD I I RUBBER DOME FOR UNDERWATER SQUND 3 Sheets-Sheet 1 Filed Jan. 16, 1945 lllllllllllllllllll 7/ JAMES W..FITZGERALD Nov. 20, 1951 J. w. FITZGERALD RUBBER DOME FOR UNDERWATER SOUND 3 Sheets-Sheet 2 Filed Jan. 16, 1945 cSIG JAMES w. FITZGERALD N 1951 J. w. FITZGERALD 7 I RUBBER DOME FOR UNDERWATER SOUND Filed Jan. 16, 1945 5 Sheets-Sheet is ILEZLE JAMES W. FITZGERALD Patented Nov. 20, 195 1 UNITED STATES PATENT OFFICE 6 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) The present invention relates in general to underwater sound equipment and in particular to underwater streamlined domes or dome struc tures for housing underwater sound projectorreceiver devices.

In underwater sound, echo ranging and listening from ships, any increase in the maximum ship's speed permissible for such operations is of great tactical importance, and to attain the highest speed permissible without objectionable vibration or noise due to turbulence, it is the practice to have the sound emitting and receiving element in a stream lined dome mounted on the bottom of the ship, sometimes to one side of the keel. However, use of the existing type of domes utilizing a thin metal shell as an underwater sound transparent wall member for the dome is met with some loss of range, the beam patterns being often 'quite badly distorted with reflection lobes appearing nearly as long as the main beam. With a view-to improvement the trend has been toward the use of thinner and thinner metal for the walls backed by a form sustaining grid or reticulate frame of stronger metal, but here a mechanical limit is reached before substantial elimination of the above disadvantage is attained. Also problems in maintenance increasing in difiiculty with decrease in the thinness of the metal walls present themselves, mainly that of maintaining good Zjoints between the thin sheet metal wall and the form sustaining grid. Here the stresses, highly concentrated at the joints due to necessarily wide spaced small area joints, tends to tear out the joint areas of the thin metal covering.

It is therefore, an object of this invention to provide an improved sound transparent wall structure whereby to make possible the construction of a streamlined underwater sound dome which shall be highly transparent to underwater sound and at the same time resistant to deformation and mechanical failure under the stresses produced by high speed underwater travel and encountered in the pitching and pounding of a high speed boat on which it may be mounted.

"-Another object is the provision of an under- "A'further object is the provision of a joint "structureadapted to the joining of sections of the improved sound transparent wall structure to each other or to other structural elements without alteration of their physical condition or interference with their sound transparency.

These and other objects are attained through an application of the discovery that the high underwater sound transparency of rubber can be taken advantage of in the'construction of an underwater streamlined sound dome when suitably combined with form sustaining means in a manner to preserve the acoustical properties of the rubber substantially undiminished, and at the same time produce a device highly resistant to deformation and mechanical failure.

Various other objects and advantages of the invention will become apparent from a perusal of the following specifications and the drawings accompanying same.

In the drawings:

Figure 1 is a reduced scale perspective view of an assembled dome.

Figure 2 is a reduced scale side elevation of a retractable dome.

Figure 3 is a top plan view partly in section and on a scale larger than that of Figure 1.

Figure 4 is a side elevation partly in section on the line 4-4 of Figure 3.

Figure 5 is a fragmentary detailed view of the portion 5 of Figure 3, with a portion of the rubber covering removed.

Figure 6 is a detailed view of an anchorage for internal structural elements.

Figure 7 shows a modified window-flange joint.

Figure 8 is a further modified window-flange J'oint.

Figure 9 is a small scale view of a flat,'bendable wall panel.

Figure 10 is a fragmentary sectional view showing the panel of Figure 9 installed.

Figure 11 is a modified form of wall structure.

Figures 12 and 13 show a modified form applicable to small domes.

A streamlined underwater dome constructed in accordance with the present invention is shown in the small scale perspective view of Figure 1, and comprises in the main a side wall section H] with its attaching flange ll forming an upper extension of the side wall, a bottom wall section 12 and a top plate l3. The side wall portion is continued upwardly in the form of an attaching skirt M for attaching the dome to the bottom of the hull of a ship sometimes to one side of the keel, the skirt portion 14 being of suflicient vertical dimension to enable the top rim to be cut to fit the hull contour and permit the side wall section ID to extend below the keel line. The

1,8 are,- provided with attaching flanges.

tice the dome is rendered free-flooding by the provision of suitable openings Hi to keep it filled with water from the surrounding 'body'of water. However, as is well understood in the art, other liquids of suitable acoustical qualities may be used.

Where the dome is to bermounted forretrao io into a well or recess in a ships hu1l,'the attaching skirt I4 is replaced by a: reducing or taper head as i d cated. at .4. in. F re 2 for at aoli aent t theusual retractable hollow shaft 5 5,

Refer n e to Fi es '3. an 5 wi l emain th mpr ved sound transparent wall. s ructure of. the present invention as used in the side. and bottom Wall sections of the. soun dome He it will seen that the sound transparent wall structure comprises a form sustaining, reticulate frame panel. [,8 of ordinary commercial expanded metal or like structure having a o erin ru or other suitable. rubber-like material in which .the .reticulate frame. member is imbedded, For

securing thewall sections in the assembled dome Structure suitable metal, attaching flanges, such .as. thefiange 20, (Figures 3; and 5.) are Secured to themargine or edges of. the suppqrting grid p ne 18 preferably by welding as indicated at 2|. The cover 19 is cured in position, preferably under pressure in a mold toelfectasecurebond between it and the form-sustaining grid. member I ,8 the pressure. acting to force. outsubstantially all of any air previously contained intherubber. While the. main body of the rzubloer coyger. is, positioned in front alo the. outside of; thearid: supp rt.

the. rubber extends; also. over he: nner. ide of;

the grid in an amountsuflieienttoinsurea sub- .stantially complete surrounding of the grid elements, as indicatedin Figures aand 4. similarly the other edges of the supportingv grid; member For example as indicated in Figuresa and 5 the top edge iswelded-totheinner face. of the attaching flange llin a mannersimilar. tothat'of; theconnection between the flange 2i] and the side 64 .8? ofthe rid frame. Also asindicated in the lower sectioned portions of Figure 4 the bottom edge of. the frame, element, [8 has welded to it an attaching flange 2.3.forattachment to the. bottom wall section I2. Thusthe entire. periphery ofthe' supporting grid panel is provided with attaching flanges forming a substantially continuous attaching frame for the grid member. 'Ijhis-will be clear upon reference to Figure 5 which shows an inside view of the upper left hand portion: 5 of Figure 3, with the. rubber removed. Here it will be.- seen how the top and side flange members II. and 20 join to form a continuous attaching 4 shown in Figure 3 so as to place the main body of the covering substance at the front of the grid member, the rubber covering extending through the grid around the grid elements to completely embed the latter. Thus a flush joint is provided Where the flanges and. the rubber covering substance meet; and to protect-- these joints from weakening by flexure of the rubber in the immediate vicinity'of the joint, cover strip 22 securecl to the flanges by seam welding or other suitable means of attaching, extend along the joints in overlapping relation with the rubber covering.

Curing of the rubber covering is effected after.

assemblageof the supporting grid and connecting flange and preferably under high pressure .to b ling the body material of the rubber covering into intimate contact with the grid elementsand thus effect a strong-bond between the grid plate and the rubber covering. The cover strips 22 and 25 are applied after thefrubber is cured. As shown in Figures 3 nd. 4. he sid wall anel section 10 c nstructed as above. descr ed extends continuously around the ides nd. fr. end of th dom while the rear edges, are. joined; throu h, th

attaching plate 20 to a streamlinediendpostn enrb r .5 of suitable struotu alm tal-and. toqwhi h hey are ecured byseam welding. Thebottom imilar] wall stru ture is constructed. a. manner to that o the side wall-member; In. andzis-miqvided with a. radially inwardly extendingeattache in flan e. 21 by whic it. is attaohed..-to'theehd post 26. and tothelowerrsimilarlx'shanedattachins flan e 3 of the... i.de wall. member Ht. "IEhe flang s 21 and. 2?.- max e. securedtogethena indicated; by suitab e. bol slfiiwitlr anintervening sket 2.9. for nderin he joint waterti ht-or inv her kn wn. manner as by: wel in i mehi h latter casetheweldesi joint max: h f awaten ixht var ety. nd theeasketdispensedwith;

teet.v the j int. betweenihel; ubber; covering and the flange v 2.3..and; 2. a..- suardstrin fiiis secured around the. ioint.betweenitheflan ea.aftehas embly, by seam, welding: to. the outer e ges or. the flanges and in. overlappin relation with; then-1h ber coverin in.theirnmediatevicinitg.oizthesipint between the .rubberoov nin andltheiflan es. .'IZO preveptiniurrto. therubbee .intifzmlmthelheat producedin welding h ieu l.. .l) 9.1:theb k tions of the rubloenv overin 4 theene ghbor ioosl of. theweldin operation. ma abeieooled. suchwelding... n

Because of, theextensionoi the attachin ifianse 2.3... normal to the-wall member.lliiwhiohlpreveli fi.'

the wall member frcnrbeing bent-.intoethedesired curve froma flat panel.formi..the-rubberoove ging la is cured to the-reinforcing ridlii inthecurved form. of the finished; wall... However;. it; to; he

pointed. out, that; thenovelpanel structurehere disclosed readily. lendsiitselfito being formeiasla flat panel as. shown. in-..Eigur.e: 95. with, 9....bottom V flange. 56. as well as the top flangefiliflatandrentending. in theplane. of theseompleted,wallepanel and later bent, to; form. avertical wall streamlined' in horizontal. contour. This;.enables-..the new frameor flange. Preferablytheflangesl landZfl are welded together along the seam 2 4 By joining the attaching langes and grid frame as i cated in Fi resB an 5 wit t t achin flanges. overlapping the marginal portion of; the outer side of the grid member, the rubber cover 1. ay e liedto e-eri with the ute ac qiz l o.

sound-window structure-to. bev used; as amnlar mentfor. an .existing1all1metal .wmdow panel simply by. cutting out; the. or ina win o rn ne and installingthe replanemeh b w ldi t r place at. the flangesfifi -Ildi Jzh$hd3ifiliiii ne i'ise ure 1O,at5.8.a d;5.9...

I te nal; br cin el m ntaia t t rm-. ht

channel beams 3| and 32 are secured to t pla es such-mana e i esliena hqwn Sir ner r ae softhe-si eiw h by;- me neo i eatures the outer side or the grid ane 18 as 'in'dicated at 34 and supports a threaded bolt 35 extending through the inner surface of the wall for attachment of the channel elements. These anchor plates with thebolts carried thereby are of course scribed structures the attaching flange is welded to the inner side of the grid panel after which the-rubber covering is applied and vulcanized to the plate to effect a strong bond betweenthe rubber and the grid panel. After assemblage of the joint as by spot welding a groove 62 formed in the rubber along the joint either in the molding or by routing out after assemblage'ofthe joint, is closed with a rubber filling 63 vulcanized or cured in place. A further modified joint structure is shown in Figure 8 where the attach- 'ing flanges 3'? are welded at 38 to the extreme edges of the grid panels. After the grid sections are joined by welding the attaching flanges to- .gether as at 39, the rubber covering 40 isapplied and cured in place, or the flanges may be welded .together after application of the rubbenProVided 7 the rubber in the vicinity of the joint is cooled during such welding. After this assembly the rubber filling 4| is applied andcured in place.

A modified form of wall structure as shownin section in Fig. 11 comprises a pair of reinforcing elements 613 and Si in the form of a mesh or network of flexible, substantially non-stretchable material for example a strong wire mesh, spaced substantially parallel and embedded in a panel I of rubber or like material. Such a wall structure has been found to offer a high resistance to bending or other deformation. Because of this quality of rigidity in the finished structure the rubber covering must be cured after formation of the structure preferably in a vulcanizing or curing mold.

Figures 12 and 13 show a modification of the invention for domes of small size, in which the form sustaining grid is comprised of flexible substantially non-stretchable material held taut by a fluid maintained under pressure within the dome. Here the wall of the dome, of rubber like material 42 is cured on to a form-sustaining grid member comprised of network or mesh of strands 43 and 44 of wire, glass fibre or other flexible, non-stretchable material of suitable strength and preferably free of voids or air pockets. Any tendency to deformation of the dome by expansion will be resisted by the substantially nonstretchable strands 4344 in tension.

The streamline form of the dome is sustained "against inwardly directed pressure by maintaining the interior filled with a suitable pressure sustaining liquid preferably seawater. However, other liquids having similar acoustical characteristics as seawater such, for example as castor oil may be used for the pressure sustaining fluid. While in Figure 13 the reinforcing strands are shown related as a simple woven mesh it is to be understood that they may be laid in any relation provided that they are so directed as to resist in tension any outward extension of the walls. To permit ready installation of a suitable hydrophone into the hollow sound dome the dome is provided with a vertically upstanding hollow *shaftfisecured to the upper sideof the dome by means of an attaching flange or ring 46 bonded to thebody material of the wall of the streamlineddome' around the opening 41 in the curing of the rubber covering; The hollow supporting shaft is secured to the attaching ring through a flange 48 and countersunk bolts 49' passing through the 'flange into threaded engagement with the attaching ring. The shaft 45 which -in-Figures-12 and 13 is shown discontinued a short distance from the dome, is of indefinite length t be determined according to the particular supporting mechanism used. The shaft acting as a supporting shaft for the dome which may be mounted' for retraction in any known or other suitable manner into a well or socket. While certain specific embodiments of the invention have been herein shown and described for the sake of disclosure it is to be understood that the invention is not limited to such specific embodimentsbut contemplates all such modifications and variations thereof as fall fairly within the scope of the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for government purposes without the payment of any royalty thereon or therefor.

What isclaimed is:

1. An underwater sound dome comprising a main form-sustaining grid panel element constituting vertical front and side walls of an inclosure streamlined in horizontal section, a vertical rear end-post member streamlined in horizontal sec- -tion; to form the rear end portion of a complete horizontal streamhned contour, rear connecting flanges connecting the ends of the side wall portions of the grid element with the end post, a top connecting flange attached to the top marginal portion of the grid element extending along the entire length of said main grid element and therebeyond into connection with the end post and the top of the rear connecting flanges and extending vertically above the grid element and rear connecting flanges, a radial connecting flange attached to the grid element near the bottom of the grid element and extending radially inwardly, a cupped bottom grid wall in the form of the lower half of a streamlined surface of revolution having an axial section contour substantially matching the horizontal section contour of said main grid element, a connecting flange attached near the rim of the cupped grid wall element and extending radially inwardly, said radial flanges being secured together to secure the cupped bottom grid element to the main grid element, a covering of sheet rubber-like material bonded to and embedding the grid elements, a horizontal top plate covering the top of the enclosure formed by the main grid element and top connecting flange, said top plate having an opening therein to provide entrance for a transducer into the interior of the dome, and a housing surrounding the opening in the top plate and extending upwardly for suspending the dome from the bottom of a ship.

2. An underwater sound dome as defined in claim 1 having spaced anchor plates secured to the main grid element and. connected by light bracing beams on the inner side of the sheet rubber-like covering.

3. An underwater sound dome as defined in claim 1 in which the housing surrounding the top plate takes the form of a tapered head of general inverted-funnel shape and a hollow shaft extending upwardly therefrom to permit retractable ans:

pension of the dome from the bottom or a ship...

4. An underwater sound transparent panel for an underwater sound dome zmain form-sustaining grid panel elementconstk tu-ting vertical front-and side walls of an en- .closu-re streamlined in horizontal .section, a vertical rear end-post member, ,rear connecting flanges connecting the ends of the side wall portions of the grid element with the end .post, a top conzment, and a covering o s eet rubber-lik m t 7 -unnamedtoancimbeddineth gndelement necting flange attached to the top marginal por tion of the grid element extending along the en.- tire length of said grid element and; therebeyond into connection with the end post and'the' top of the rear connecting flanges, a radial connecting flange attached to the grid element near'the bottom of the grid element and extending radially inwardly, a cupped bottom grid walllnthetorm of the lower half of a streamlined surface ofrevolution having an axial sectiorr con-tour substantially matching the horizontal section contour of said main grid element, a connecting flange attached near the rim of the cupped grid wall. element and'extending radiallyinwardly, sal'd'rad'ial 35 flanges being secured together "to secure: the

6.: An underwater sou dom as la e claim 4 hav n an nte n acin file le -i v e cureaito the in e su ac a s i aid r 1 a element and exten in d a o a jomn r h top-of said end post to-near a forward portion [of the radial flange of the grid element whereby the dome. structure isbraced ina plane diagonalto the vertical post and diagonal to theplane or the g nnrnnnnces CITED The following references areof record-in the file er this patent: i V

' UNITED STATES- PATENTS .Num'ber Name 7 Date 76 ,573 Mundy Aug; 23, 1904 985.1 6.? Hanlon Feb. 28,1911

1,345,717 Thomas l July 6,1920

1,545,328 Holland July 7, 1925 1.994.495 Williams Mar. 19 1935 2108,7122 Miedel F'ebi1'5, I938 2,116,106 Emmert May 3, I938 2,212,373" LitlegJr. Aug. 20) I940 2,218,351 Crowel-l Oct. 15, 1940 2,417,829 Keller Mar. 25,1946? 2,41'7Q830 Keller Mar. 25, I947 2360,274 Benioff Feb. 1,7194

FOREIGN PATENTS Number Country 7 Date 126,298 Great Britain Apr. 29, 1 F-20 

